pragma solidity >=0.4.22 <0.6.0; contract Migrations { address public owner; uint public last_completed_migration; modifier restricted() { if (msg.sender == owner) { _; } } constructor() public { owner = msg.sender; } function setCompleted(uint completed) public restricted { last_completed_migration = completed; } function upgrade(address new_address) public restricted { Migrations upgraded = Migrations(new_address); upgraded.setCompleted(last_completed_migration); } }